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Equity Compensation Plans - Stock Incentive Plan (Details Textual) - Stock Incentive Plan 2005 | 1 Months Ended | 12 Months Ended |
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May 31, 2020 shares | Dec. 31, 2020 shares | Apr. 30, 2018 shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Increase in number of shares approved for issuance under incentive plan | 3,600,000 |  |
Number of shares approved for issuance under incentive plan | 25,000,000.0 |  | 21,400,000
Number of shares counted for every share granted |  | 2 |
Stockholder approved shares available for issuance |  | 5,800,000 |
Stockholder approved shares available for grant |  | 5,500,000 |

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- Definition Shares granted in the form of a performance unit award, restricted stock award, or stock bonus award are counted toward the aggregate number of shares of common stock available for issuance as two shares for every one share granted or issued in payment of such award. + References No definition available. + Details
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- Definition Number of additional shares authorized for issuance under share-based payment arrangement. + References No definition available. + Details
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- Definition Number of shares authorized for issuance under share-based payment arrangement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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- Definition The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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